Core B: Field Core?Abstract The Health and Aging in Africa: Longitudinal Studies of an INDEPTH Community (HAALSI) Program aims to develop a unique platform for understanding patterns and trends in health and well-being of older adults by incorporating two new waves of longitudinal survey data with the HAALSI baseline and leveraging the strong existing infrastructure of routine demographic and health surveillance in Agincourt, South Africa. The principal goals of the Field Core (Core B) are to establish rigorous, standardized systems to support data collection, manage household surveys, follow all participants in the baseline survey, and integrate data on mortality and selected demographic information from the Agincourt Health and Demographic Surveillance System (HDSS). The survey will be the central source for new primary data essential for the analyses proposed in the five projects of the HAALSI Program, focused on Alzheimer?s disease and related dementias (ADRD), cardiometabolic disease (CMD), HIV, public policy, and multimorbidity. To meet these goals, Core B will develop and implement common systems of data collection, data capture and data management. Core B will coordinate pilot testing of all new data collection instruments and procedures and will produce final data collection tools through close collaboration with the Data Management and Analysis Core (Core C). Core B will work with the Agincourt HDSS team to create well-defined field procedures based on the HDSS routine surveillance and the experience gained collecting baseline data during in the previous funding period, to implement efficient field operations, and to ensure that data collection teams reach all participants in each survey wave. Core B will develop Standard Operating Procedures (SOPs), train all site-based personnel, and develop and implement appropriate quality assurance monitoring. Moreover, Core B will produce continuous progress reports that will be discussed with the PIs of all projects to ensure that corrections are implemented when necessary so that final data collected is complete and of highest quality. Finally, Core B will implement existing and newly created cohort maintenance systems to track the cohort of 5,059 individuals who participated in the HAALSI baseline data collection. These systems will allow for complete follow-up of the cohort; the identification, tracking and follow-up of migrants; and the registration of deaths soon after the event so that a verbal autopsy can be undertaken in a timely manner. The work in Core B will take advantage of the extensive experience of the Agincourt field team in implementing complex surveys of this nature.